Primary Feedstock Research Articles

Enzymatic digestibility and pretreatment degradation products of AFEX‐treated hardwoods (Populus nigra)

There is a growing need to find alternatives to crude oil as the primary feed stock for the chemicals and fuel industry and ethanol has been demonstrated to be a viable alternative. Among the various feed stocks for producing ethanol, poplar (Populus nigra x Populus maximowiczii) is considered to have great potential as a biorefinery feedstock in the United States, due to their widespread availability and good productivity in several parts of the country. We have optimized AFEX pretreatment conditions (180 degrees C, 2:1 ammonia to biomass loading, 233% moisture, 30 minutes residence time) and by using various combinations of enzymes (commercical celluloses and xylanases) to achieve high glucan and xylan conversion (93 and 65%, respectively). We have also identified and quantified several important degradation products formed during AFEX using liquid chromatography followed by mass spectrometry (LC-MS/MS). As a part of degradation product analysis, we have also quantified oligosaccharides in the AFEX water wash extracts by acid hydrolysis. It is interesting to note that corn stover (C4 grass) can be pretreated effectively using mild AFEX pretreatment conditions, while on the other hand hardwood poplar requires much harsher AFEX conditions to obtain equivalent sugar yields upon enzymatic hydrolysis. Comparing corn stover and poplar, we conclude that pretreatment severity and enzymatic hydrolysis efficiency are dictated to a large extent by lignin carbohydrate complexes and arabinoxylan cross-linkages for AFEX.

“Green” Chemicals from Renewable Agricultural Biomass - A Mini Review

Recently, utilization of renewable resources to replace petroleum as a primary feedstock for liquid fuels, chemicals and materials has become a topic of interest around the world. It is intriguing due to rising oil prices, the negative effects of petroleum on the environment and the advantages of renewable resources, such as their abundance and sustainability. Herein, the possibilities for biobased chemicals prepared from renewable resources are reviewed. The most popular feedstocks for commodity and specialty chemicals are carbohydrates as they account for approximately 95% of the biomass produced annually. The conversion routes, including chemical and biological routes, direct extraction, and selected technical advancements are discussed. Examples of select biochemcials, their conversion pathways from biomass, and their derivatives and potential applications are indentified.

Glycerin as a Renewable Feedstock for Epichlorohydrin Production. The GTE Process

AbstractA significant improvement in a process to produce epichlorohydrin through the use of glycerin as renewable feedstock is presented. The glycerin to epichlorohydrin (GTE) process proceeds in two chemical steps. In the first step, glycerin is hydrochlorinated with hydrogen chloride gas at elevated temperature and pressure to a mixture of 1,3‐DCH (1,3‐dichlorohydrin, 1,3‐dichloropropan‐2‐ol) and 2,3‐DCH (2,3‐dichlorohydrin, 2,3‐dichloropropan‐1‐ol), using a carboxylic acid catalyst. In the second step, the mixture of dichlorohydrins is converted to epichlorohydrin with a base. This solventless process represents an economically and environmentally advantageous, atom‐efficient process to an existing commodity chemical that can employ a renewable resource for its primary feedstock.

Solid Oxide Fuel Cells: Operating Principles, Current Challenges, and the Role of Syngas

Syngas mixtures are excellent fuels for solid-oxide fuel cells (SOFC). Depending on the primary feedstock and the processing technology to produce the syngas, the composition (primarily mixtures of H2 and CO, but often including CH4, H2O, CO2, N2, and other impurities) can vary considerably. Thus, it is important to understand how SOFCs perform with alternative syngas mixtures. Syngas composition can affect materials selection, system design, and operating conditions. To assist understanding and interpreting performance, the article first reviews the basic principles governing SOFC chemistry and electrochemistry. The article also discusses alternative materials and system architectures, especially in the context of syngas fuels. A detailed computational model for a particular tubular, anode-supported, cell is used to compare SOFC performance using different syngas compositions. The syngas mixtures are derived from several processes, including partial oxidation (CPOx) or steam reforming of methane and dodecane, and gasification of coal or biomass.

Cargill-Novozymes alliance

Biomass, the most abundant carbon source on the planet, may in the future become the primary feedstock for production of fuels and chemicals, replacing fossil feedstocks. This will, however, require development of cell factories that can convert both C6 and C5 sugars present in lignocellulosic biomass into the products of interest. We engineered Saccharomyces cerevisiae for production of 3-hydroxypropionic acid (3HP), a potential building block for acrylates, from glucose and xylose. We introduced the 3HP biosynthetic pathways via malonyl-CoA or β-alanine intermediates into a xylose-consuming yeast. Using controlled fed-batch cultivation, we obtained 7.37±0.17 g 3HP L−1 in 120 hours with an overall yield of 29±1% Cmol 3HP Cmol−1 xylose. This study is the first demonstration of the potential of using S. cerevisiae for production of 3HP from the biomass sugar xylose.

Dual Nanoparticle/Substrate Control of Catalytic Dehydrogenation

Saturated hydrocarbons, or alkanes (C{sub n}H{sub 2n+2}), are abundant in petroleum and can be converted to alkenes (C{sub n}H{sub 2n}) by dehydrogenation. Alkenes, also known as unsaturated hydrocarbons, are easy to polymerize and are the primary feedstock of the petrochemical industry, especially ethene (n=2) and propene (n = 3). Efficient catalytic dehydrogenation is therefore a major industrial objective. It has been found that oxidative catalytic dehydrogenation, that is, a process assisted by both a solid catalyst and a flow of oxygen gas, is most practical because of higher system longevity. Chromia/alumina catalytic systems have been widely adopted by industry. They have also been the subject of scientific studies seeking understanding that may help optimization of the process.

Microscopic analysis of corn fiber using starch‐ and cellulose‐specific molecular probes

Ethanol is the primary liquid transportation fuel produced from renewable feedstocks in the United States today. The majority of corn grain, the primary feedstock for ethanol production, has been historically processed in wet mills yielding products such as gluten feed, gluten meal, starch, and germ. Starch extracted from the grain is used to produce ethanol in saccharification and fermentation steps; however the extraction of starch is not 100% efficient. To better understand starch extraction during the wet milling process, we have developed fluorescent probes that can be used to visually localize starch and cellulose in samples using confocal microscopy. These probes are based on the binding specificities of two types of carbohydrate binding modules (CBMs), which are small substrate-specific protein domains derived from carbohydrate degrading enzymes. CBMs were fused, using molecular cloning techniques, to a green fluorescent protein (GFP) or to the red fluorescent protein DsRed (RFP). Using these engineered probes, we found that the binding of the starch-specific probe correlates with starch content in corn fiber samples. We also demonstrate that there is starch internally localized in the endosperm that may contribute to the high starch content in corn fiber. We also surprisingly found that the cellulose-specific probe did not bind to most corn fiber samples, but only to corn fiber that had been hydrolyzed using a thermochemical process that removes the residual starch and much of the hemicellulose. Our findings should be of interest to those working to increase the efficiency of the corn grain to ethanol process.

Critical issues in heat transfer for fuel cell systems

The current state of the art in fuel cell system development will be reviewed with an emphasis of the critical issues on heat transfer. The heat transfer issues for both PEM based systems and SOFC based fuel cell systems will be addressed. For systems that are based on hydrocarbon fuels a reforming step is needed and critical heat transfer issues are also present in this fuel processing part of the system where the primary feedstock is converted to reformate. Also, in both the PEM and SOFC fuel cell itself, heat transfer is a critical issue. It will be shown what are the implications of the fuel cell heat transfer to the total system architecture for the various fuel cell applications (stationary power, transport). The heat transfer issues in fuel cell system development will be clarified with several examples.

Corn Stover Impacts on Near‐Surface Soil Properties of No‐Till Corn in Ohio

Corn (Zea mays L.) stover is a primary biofuel feedstock and its expanded use could help reduce reliance on fossil fuels and net CO2 emissions. Excessive stover removal may, however, negatively impact near‐surface soil properties within a short period after removal. We assessed changes in soil crust strength, bulk density (ρb), and water content over a 1‐yr period following a systematic removal or addition of stover from three no‐till soils under corn in Ohio. Soils from ongoing experiments at the North Appalachian Experimental Watershed (NAEW), Western Agricultural Experiment Station (WAES), and Northwestern Agricultural Experiment Station (NWAES) of Ohio Agricultural Research and Development Center (OARDC) were studied. Six stover treatments of 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200)% were imposed on 3 by 3 m plots corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha−1 of stover, respectively. Cone index (CI), shear strength (SHEAR), ρb, and volumetric water content (θv) were measured monthly from June through December 2004 and in May 2005. Effects of stover removal on increasing CI and SHEAR were soil‐specific. Stover removal consistently increased ρb and decreased θv across soils (P < 0.01). Compared with the normal stover treatment (T100), doubling the amount of stover (T200) did not significantly affect soil properties except θv where, after 1 yr, T200 increased θv by 1.3 to 1.6 times compared with T100 across all sites (P < 0.05). After 1 yr, complete stover removal (T0) increased CI by 1.4 times and SHEAR by 1.3 times at NAEW compared with T100 and T75, but CI increases at other sites were nonsignificant. At NWAES, T0 increased SHEAR by 26% compared with T100 (P < 0.05). The T0 decreased θv by two to four times except in winter months and increased ρb by about 10% compared with T100 (P < 0.05). In a short‐term test, stover removal resulted in increased soil crust strength and reduced soil water content.

Peaking of World Oil Production and Its Mitigation

Publisher Summary The world has never faced a problem like the peaking of oil. Previous energy transitions—such as wood to coal or coal to oil—were gradual and evolutionary; oil peaking will be abrupt and revolutionary. Satisfying the increasing oil demand not only requires continuing to produce older oil fields with their declining production but also requires finding new ones, capable of producing sufficient quantities of oil to both compensate for the shrinking production from older fields and provide the increase demanded by the market. A number of options exist that can be applied to lessen oil dependence and reduce economic vulnerability to oil price increases. They include reduction in energy demand, methods to increase oil production, and the introduction of alternative fuels that can substitute for oil in key market applications. The implementation of mitigation strategies will require an intense effort over decades. There are a number of factors that could conceivably impact the peaking of world oil production. Among the upsides, or factors that might ease the problems of world oil peaking, is the possibility that the pessimists are wrong again and peaking does not occur for many decades. Alternatively, Middle East oil reserves turn out to be much larger than publicly stated or a number of new super-giant oil fields are found and brought into production well before oil peaking occurs.

Low-tonnage production of motor fuels at remote fields

A reliable supply of motor fuels for automotive transport is one of the most important factors in normal functioning of the economy of any country. Crude oil and gas condensate are the traditional primary feedstock for manufacture of motor fuels — automotive gasolines and diesel fuels. In Russia, despite the large production volumes and enormous reserves of this hydrocarbon feedstock, the problem of reliably supplying different regions of the country with motor fuels, especially the Extreme North, Siberia, and Kamchatka, is pressing. Consumers of motor fuels are frequently separated from manufacturers by thousands of kilometers.

Advanced Processing and Properties of Thixotropic Formed Components Based on Partially Melted Magnesium

Contrary to the manufacture of aluminium components in the semi‐solid, thixotropic state the production of magnesium based components by semi‐solid techniques is still uncommon. For this reason, the advantage of this production method is analysed with regard to the commercial magnesium alloy AZ80. The objective of this research is semi‐solid‐casting (SSC) of AZ80 for the production of a light weight component in near‐net‐shape quality and with advanced properties.Using extruded primary feedstock material, the behaviour and the advantages are investigated. Billets with a weight of up to 2 kg are heated up into a semi‐solid state. To avoid any risk of self‐ignition of the material an automatic, temperature controlled induction heating system is used. To achieve an optimum homogeneous grain structure the induction heating power is varied making use of a process control system based on power‐time‐curves. The heated billets are transported in the soft semi‐solid condition from the induction heating system to a die casting machine to produce components with wall thickness’ between 2 and 10 mm. After forming of the components, the influence of heat treatment on the grain structure and especially on the mechanical properties is determined to provide parts with optimised characteristics.To compare the properties of the special globular grain and microstructure, the results of various static and dynamic tests are analysed. It is found that components can be manufactured with a magnesium alloy in a thixotropic state in near‐net‐shape quality, with low porosity and with excellent mechanical properties like elongation of up to 15%.

‘Greening’ the chemical industry: research and development priorities for biobased industrial products

AbstractThe chemical industry developed over the past century using petroleum as its primary feedstock. A variety of economic, political and social forces are now leading the chemical industry to use or consider renewable plant‐based feedstocks in addition to or instead of petroleum. The next century may see a gradual transition away from petroleum as the primary feedstock for chemicals, materials and liquid fuels. If this transition is to occur, and if the chemical industry is to become more sustainable, a considerable amount of research must be done. This paper summarizes the research and development priorities for a more sustainable, or ‘green’, chemical industry based on renewable plant resources and relies heavily on a recent report of the National Research Council (NRC) of the United States. Copyright © 2003 Society of Chemical Industry

Cheaper by the Half-Dozen

The value of many primary chemical feedstocks can be limited by the value of by-products that must also be sold. For example, the current synthesis of methanesulfonic acid (MSA) proceeds by means of the chlorine oxidation of methylmercaptan, and 6 moles of hydrochloric acid are produced for every mole of MSA. Mukhopadhyay and Bell report on a method in which methane is sulfonated directly, thereby avoiding the production of chlorine-containing byproducts. They use SO2 as the sulfate source and K2S2O8 as an oxidant; the reactions are run at high pressure in triflic acid. Various calcium salts, which have been shown to be effective catalysts in methane carbonylation, were tested, and the highest yields (22% conversion after 26 hours of reaction) were obtained with CaO2. Further efforts will be directed at replacing K2S2O8 with O2 as the oxidant.—PDS

Novel gene expression profiles define the metabolic and physiological processes characteristic of wood and its extractive formation in a hardwood tree species, Robinia pseudoacacia.

Wood is of critical importance to humans as a primary feedstock for biofuel, fiber, solid wood products, and various natural compounds including pharmaceuticals. The trunk wood of most tree species has two distinctly different regions: sapwood and heartwood. In addition to the major constituents, wood contains extraneous chemicals that can be removed by extraction with various solvents. The composition and the content of the extractives vary depending on such factors as, species, growth conditions, and time of year when the tree is cut. Despite the great commercial and keen scientific interest, little is known about the tree-specific biology of the formation of heartwood and its extractives. In order to gain insight on the molecular regulations of heartwood and its extractive formation, we carried out global examination of gene expression profiles across the trunk wood of black locust (Robinia pseudoacacia L.) trees. Of the 2,915 expressed sequenced tags (ESTs) that were generated and analyzed in the current study, 55.3% showed no match to known sequences. Cluster analysis of the ESTs identified a total of 2278 unigene sets, which were used to construct cDNA microarrays. Microarray hybridization analyses were then performed to survey the changes in gene expression profiles of trunk wood. The gene expression profiles of wood formation differ according to the region of trunk wood sampled, with highly expressed genes defining the metabolic and physiological processes characteristic of each region. For example, the gene encoding sugar transport had the highest expression in the sapwood, while the structural genes for flavonoid biosynthesis were up-regulated in the sapwood-heartwood transition zone. This analysis also established the expression patterns of 341 previously unknown genes.

Oxygenated aromatic compounds from renewable resources: motivation, opportunities, and adsorptive separations

Over the last 50 years petroleum has become the primary feedstock for industrial organic chemical production. Over the next 50 years it is anticipated that there will be a growing use of renewable feedstocks in chemical manufacturing. In this review, the motivations for developing alternatives to petro-chemicals are discussed, and we highlight exciting advances in biotechnology that promise to make biomass-based feedstocks more attractive in the future. We argue that separations remain a key bottleneck to the recovery of organic chemicals from renewable resources. Finally, we consider our research to understand the mechanistic interactions responsible for adsorption onto polymeric adsorbents. We provide examples illustrating how knowledge of hydrogen-bonding interactions can be exploited for separating chemicals from renewable resources. We especially focus on oxygenated aromatic compounds (OACs) that are abundant in biomass-based feedstocks.

High Natural Gas Prices Cripple Some Chemical Producers

As if a cyclical trough, an economic crisis in Asia, and the high petroleum prices that have plagued the chemical industry in recent years were not enough, now the chemical industry has to worry about the weather. With unseasonably low temperatures in much of the U.S. this winter, natural gas prices have hit unprecedented highs. According to the Energy Information Administration, New York Mercantile Exchange futures contracts for January 2001 closed out in December 2000 at $9.98 per million Btu. That's more than four times the 1999 closing price of January 2000 futures. The high prices are exacting a toll on petrochemical producers that rely on natural gas as a primary feedstock. Ethane and propane have gone up accordingly, and that has had a dramatic impact on the cost to produce ethylene, according to Mark A. Eramo, an analyst with Houston-based Chemical Market Associates. Eramo says about 70% of ethylene ...

Optimization of the Heat Supply and Recovery Scheme in Delayed Coking Chemical Engineering Systems

The reasons for using a furnace for heating the primary feedstock and excess number of condensers on existing type 21‐10/300 delayed coking plants (DCP) are revealed. A variant of operation of the type 21‐10/600 DCP using a heat‐exchange system is proposed. It was shown that if heat‐exchange equipment of the optimum type‐sizes is used, it is no longer necessary to use a furnace for heating the primary feedstock and the number of terminal condensers can be reduced. All of this allows reducing fuel consumption, stack gas emissions, and consumption of coolant in the condensers.

Characterization of Compost Produced at a Golf Course: Impact of Historic Mercury Accumulations In Putting Green Soil

This paper reports on the physical and chemical properties of feedstock and compost materials used at the Clear Lake Golf Course located in southwestern Manitoba. The compost was found to have a very low organic matter content (range = 9.1 to 13.2%) and a low moisture content (27.8 to 32.8%). To improve the compost quality, two recommendations were made: (1) a composting pad should be installed to prevent soil contamination and (2) the moisture content should be monitored, particularly during the curing stage. The compost contained Hg concentrations ranging from 3.16 to 6.1 mg kg−1. The grass clippings, the primary feedstock material, had Hg concentrations ranging from 8.53 to 20.2 mg kg−1. The putting green soil Hg concentration ranged from 60.7 to 90.8 mg kg−1. Elevated Hg levels may have been due to previous mercurial fungicide use and all the values were well above the Canadian compost and soil guideline values of 0.8 and 6.6 mg kg−1, respectively. It was estimated that 104.4 kg of Hg has accumulated in the top 8 cm of the putting green soil, which cover an area of 9,290 m2. Based on a Hg flow analysis conducted on the solid materials entering and leaving the putting green soil, a passive remediation approach was recommended that involved: (1) removal of the aeration cores, (2) restrictions on the compost use, (3) construction of a composting pad, and (4) the periodic monitoring of the soil and compost Hg concentrations. Calculations suggested the soil would reach the soil quality guideline value in approximately one hundred years. This is a long period of time, and, as the data suggests a degree of bioavailability, the impact of the long-term exposure to golf course staff must be determined. As there are thousands of golf courses in North America that may have been treated with mercurial fungicide, a health risk assessment should be done on the Hg exposure levels during the handling and processing of the aeration cores and grass clippings.

Rheological characterization of metal powders after various loading paths : P. Mosbah et al (UJF/INPG/CRNS, Genoble, France)

Metal Additive Manufacturing (AM) has begun its revolution in various high value industry sectors through enabling design freedom and alleviating laborious machining operations during the production of geometrically complex components. The use of powder bed fusion (PBF) techniques such as Selective Laser Melting (SLM) also promotes material efficiency where unfused granular particles are recyclable after each forming operation in contrast to conventional subtractive methods. However, powder characteristics tend to deviate from their pre-process state following different stages of the process which could affect feedstock behaviour and final part quality. In particular, primary feedstock characteristics including granulometry and morphology must be tightly controlled due to their influence on powder flow and packing behaviour as well as other corresponding attributes which altogether affect material deposition and subsequent laser consolidation. Despite ongoing research efforts which focused strongly on driving process refinement steps to optimise the SLM process, it is also critical to understand the level of material sensitivity towards part forming due to granulometry changes and tackle various reliability as well as quality issues related to powder variation in order to further expand the industrial adoption of the metal additive technique. In this review, the current progress of Metal AM feedstock and various powder characteristics related to the Selective Laser Melting process will be addressed, with a focus on the influence of powder granulometry on feedstock and final part properties.